Final answer:
Among the given options, (CH₃)₂CHCH₂Cl is the secondary alkyl halide since the chlorine is attached to a carbon atom that is bonded to two other carbon atoms.
Step-by-step explanation:
To determine which compound is a secondary alkyl halide, we will look at the carbon atom that the halogen is attached to. A secondary alkyl halide has a halogen atom attached to a carbon atom that is in turn bonded to two other carbon atoms. Therefore, option (a) (CH₃)₂CHCH₂Cl is a secondary alkyl halide as the chlorine is bonded to a carbon that is attached to two other carbon atoms. Option (b) is not a secondary alkyl halide because the chlorine is bonded to a carbon attached to three other carbons, making it tertiary. Option (c), (CH₃)₂CHCHClCH₃, is not a secondary alkyl halide because the chlorine bearing carbon is bonded to only one other carbon making it primary. Lastly, option (d) (CH₃)₂CClCH₂CH₃ contains a chlorine atom attached to a tertiary carbon, as the carbon is bonded to three other carbons. Thus, the only secondary alkyl halide among the given compounds is (CH₃)₂CHCH₂Cl.